<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Float</title>
    <style>
        .box1 {
            width: 200px;
            height: 200px;
            background-color: red;
            text-align: center;
            line-height: 200px;
            float: left;
        }

        .box2 {
            width: 300px;
            height: 300px;
            background-color: green;
            text-align: center;
            line-height: 300px;
            float: left;
        }

        .box3 {
            width: 200px;
            height: 200px;
            background-color: blue;
            text-align: center;
            line-height: 200px;
            color: white;
            float: left;
        }

              .box4 {
            width: 100%;
            height: 200px;
            background-color: #7d7d8b;
            text-align: center;
            line-height: 200px;
            color: white;

        }
    </style>
</head>
<body>
<div class="box1">1</div>
<div class="box2">2</div>
<div class="box3">3</div>

<div class="box4">Hello Float</div>
</body>
</html>